2brt: Difference between revisions
No edit summary |
No edit summary |
||
| Line 1: | Line 1: | ||
[[Image:2brt.gif|left|200px]] | [[Image:2brt.gif|left|200px]] | ||
'''ANTHOCYANIDIN SYNTHASE FROM ARABIDOPSIS THALIANA COMPLEXED WITH NARINGENIN''' | {{Structure | ||
|PDB= 2brt |SIZE=350|CAPTION= <scene name='initialview01'>2brt</scene>, resolution 2.20Å | |||
|SITE= <scene name='pdbsite=AC1:Nar+Binding+Site+For+Chain+A'>AC1</scene> | |||
|LIGAND= <scene name='pdbligand=FE2:FE+(II)+ION'>FE2</scene>, <scene name='pdbligand=AKG:2-OXYGLUTARIC+ACID'>AKG</scene> and <scene name='pdbligand=NAR:NARINGENIN'>NAR</scene> | |||
|ACTIVITY= [http://en.wikipedia.org/wiki/Leucocyanidin_oxygenase Leucocyanidin oxygenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.14.11.19 1.14.11.19] | |||
|GENE= | |||
}} | |||
'''ANTHOCYANIDIN SYNTHASE FROM ARABIDOPSIS THALIANA COMPLEXED WITH NARINGENIN''' | |||
==Overview== | ==Overview== | ||
| Line 7: | Line 16: | ||
==About this Structure== | ==About this Structure== | ||
2BRT is a [ | 2BRT is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Arabidopsis_thaliana Arabidopsis thaliana]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2BRT OCA]. | ||
==Reference== | ==Reference== | ||
Structural and mechanistic studies on anthocyanidin synthase catalysed oxidation of flavanone substrates: the effect of C-2 stereochemistry on product selectivity and mechanism., Welford RW, Clifton IJ, Turnbull JJ, Wilson SC, Schofield CJ, Org Biomol Chem. 2005 Sep 7;3(17):3117-26. Epub 2005 Aug 1. PMID:[http:// | Structural and mechanistic studies on anthocyanidin synthase catalysed oxidation of flavanone substrates: the effect of C-2 stereochemistry on product selectivity and mechanism., Welford RW, Clifton IJ, Turnbull JJ, Wilson SC, Schofield CJ, Org Biomol Chem. 2005 Sep 7;3(17):3117-26. Epub 2005 Aug 1. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/16106293 16106293] | ||
[[Category: Arabidopsis thaliana]] | [[Category: Arabidopsis thaliana]] | ||
[[Category: Leucocyanidin oxygenase]] | [[Category: Leucocyanidin oxygenase]] | ||
| Line 29: | Line 38: | ||
[[Category: vitamin c]] | [[Category: vitamin c]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 16:05:54 2008'' | ||
Revision as of 17:05, 20 March 2008
| |||||||
| , resolution 2.20Å | |||||||
|---|---|---|---|---|---|---|---|
| Sites: | |||||||
| Ligands: | , and | ||||||
| Activity: | Leucocyanidin oxygenase, with EC number 1.14.11.19 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
ANTHOCYANIDIN SYNTHASE FROM ARABIDOPSIS THALIANA COMPLEXED WITH NARINGENIN
OverviewOverview
During the biosynthesis of the tricyclic flavonoid natural products in plants, oxidative modifications to the central C-ring are catalysed by Fe(ii) and 2-oxoglutarate dependent oxygenases. The reactions catalysed by three of these enzymes; flavone synthase I, flavonol synthase and anthocyanidin synthase (ANS), are formally desaturations. In comparison, flavanone 3beta-hydroxylase catalyses hydroxylation at the C-3 pro-R position of 2S-naringenin. Incubation of ANS with the unnatural substrate (+/-)-naringenin results in predominantly C-3 hydroxylation to give cis-dihydrokaempferol as the major product; trans-dihydrokaempferol and the desaturation product, apigenin are also observed. Labelling studies have demonstrated that some of the formal desaturation reactions catalysed by ANS proceed via initial C-3 hydroxylation followed by dehydration at the active site. We describe analyses of the reaction of ANS with 2S- and 2R-naringenin substrates, including the anaerobic crystal structure of an ANS-Fe-2-oxoglutarate-naringenin complex. Together the results reveal that for the 'natural' C-2 stereochemistry of 2S-naringenin, C-3 hydroxylation predominates (>9 : 1) over desaturation, probably due to the inaccessibility of the C-2 hydrogen to the iron centre. For the 2R-naringenin substrate, desaturation is significantly increased relative to C-3 hydroxylation (ca. 1 : 1); this is probably a result of both the C-3 pro-S and C-2 hydrogen atoms being accessible to the reactive oxidising intermediate in this substrate. In contrast to the hydroxylation-elimination desaturation mechanism for some ANS substrates, the results imply that the ANS catalysed desaturation of 2R-naringenin to form apigenin proceeds with a syn-arrangement of eliminated hydrogen atoms and not via an oxygenated (gem-diol) flavonoid intermediate. Thus, by utilising flavonoid substrates with different C-2 stereochemistries, the balance between C-3 hydroxylation or C-2, C-3 desaturation mechanisms can be altered.
About this StructureAbout this Structure
2BRT is a Single protein structure of sequence from Arabidopsis thaliana. Full crystallographic information is available from OCA.
ReferenceReference
Structural and mechanistic studies on anthocyanidin synthase catalysed oxidation of flavanone substrates: the effect of C-2 stereochemistry on product selectivity and mechanism., Welford RW, Clifton IJ, Turnbull JJ, Wilson SC, Schofield CJ, Org Biomol Chem. 2005 Sep 7;3(17):3117-26. Epub 2005 Aug 1. PMID:16106293
Page seeded by OCA on Thu Mar 20 16:05:54 2008